package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

@Component
@Slf4j
public class CacheClient {
    private StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }
    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }
    public void setWithLogicalExpire(String key, Object value,Long time, TimeUnit unit){
        //设置逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        //写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(redisData));
    }

    /**
     * 解决缓存穿透的工具类
     *
     * @param id
     * @return
     */

    public <R, ID> R queryWithPassThrough(
            String Prefix, ID id, Class<R> type, Function<ID,R> dbfallback,Long time, TimeUnit unit) {
        //1.从redis中查询缓存
        String key = Prefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        //2.判断缓存是否命中
        if (StrUtil.isNotBlank(json)) {
            //3.如果命中，直接返回店铺信息
            R r = JSONUtil.toBean(json, type);
            return r;
        }
        if (json != null) {
            //命中返回空对象
            return null;
        }
        //4.如果未命中，根据id查询数据库
        R r = dbfallback.apply(id);
        //5.数据库中不存在，将空值写入redis
        if (r == null) {
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            //返回错误信息
            return null;
        }
        //6.数据库中存在，写入redis
        this.set(key,r,time,unit);
        //7.返回店铺信息
        return r;
    }
    public static final ExecutorService NEW_FIXED_EXECUTOR = Executors.newFixedThreadPool(10);
    /**
     * 解决缓存击穿的工具类
     * @param id
     * @return
     */
    public <R,ID> R queryWithLogicalExpire(
            String keyPrefix,ID id,Class<R> type,Function<ID,R> dbFallback,Long time, TimeUnit unit) {
        //1.从redis中查询缓存
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        //2.判断缓存是否命中
        if (StrUtil.isBlank(json)) {
            //3.如果未命中，直接返回null
            return null;
        }

        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1未过期，直接返回店铺信息
            return r;
        }
        //5.2已过期，需要缓存重建
        //6.重建缓存
        //6.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean islocked = tryLock(lockKey);
        //6.2判断是否获取锁成功
        if (islocked){
            if (expireTime.isAfter(LocalDateTime.now())) {
                //5.1未过期，直接返回店铺信息
                return r;
            }
            //6.3成功，开启独立线程，实现缓存重建
            NEW_FIXED_EXECUTOR.submit(() -> {
                try {
                    //查询数据库
                    R r1 = dbFallback.apply(id);
                    //写入redis
                    setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }
            });
        }
        //6.4返回过期的商铺信息
        return r;
    }

    boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    void unLock(String key){
        stringRedisTemplate.delete(key);
    }



}
